Silicone-substituted cinnamamide/malonamide/malonate compounds and photoprotective compositions comprised thereof

ABSTRACT

Novel silicone-substituted cinnamamide/malonamide/malonate compounds having the structural formulae (1) and (2): ##STR1## in which A is a radical of formula (3): ##STR2## are well suited for the photoprotection of human skin and/or hair against the damaging effects of UV-A and UV-B irradiation, particularly solar radiation, and are also useful for photoprotecting such UV-sensitive substrates as plastics.

CROSS-REFERENCE TO COMPANION APPLICATION

Our copening application Ser. No. 08/980,307 filed concurrently herewithand assigned to the assignee hereof.

BACKGROUND OF THE INVENTION

1. Technical Field of the Invention

The present invention relates to novel cinnamamide, benzalmalonamide andbenzalmalonate compounds bearing short-chain silicone substituents onthe aromatic moieties thereof.

This invention also relates to compositions of matter, in particularcosmetic compositions, comprising the above novel compounds, which areespecially well suited for the photoprotection of the skin and/or thehair against the deleterious effects of UV radiation, in particularsolar radiation.

2. Description of the Prior Art

It is known to this art that light radiation of wavelengths of from 280nm to 400 nm promotes tanning of the human epidermis, and that lightradiation of wavelengths more particularly of from 280 to 320 nm, i.e.,UV-B irradiation, causes skin burning and erythema which can impair thedevelopment of a natural tan. For these reasons, as well as foraesthetic reasons, there is an increasing demand for means ofcontrolling this natural tanning in order to thereby control the colorof the skin. This UV-B radiation must thus be screened from the skin.

It is also known to this art that UV-A radiation, of wavelengths of from320 to 400 nm, which tan the skin, also adversely affects it, especiallyin the case of sensitive skin or skin which is continually exposed tosolar radiation. UV-A rays especially cause a loss in the elasticity ofthe skin and the appearance of wrinkles, promoting premature skin aging.Such irradiation promotes triggering of the erythemal reaction oramplifies this reaction in certain individuals and may even be thesource of phototoxic or photoallergic reactions. Thus, for aesthetic andcosmetic reasons, such as conservation of the natural elasticity of theskin, for example, an ever-increasing number of individuals wish tocontrol the effect of UV-A rays on their skin, it is desirable to alsoscreen out UV-A radiation.

A wide variety of compounds suited for photoprotection (UV-A and/orUV-B) of the skin are known to this art.

Most of these are aromatic compounds exhibiting absorption of UVradiation in the region from 280 to 315 nm, or in the region from 315 to400 nm, or in both of these regions. They are typically formulated intoantisun or sunscreen compositions which are in the form of an emulsionof oil-in-water type (namely, a cosmetically acceptable vehicle, diluentor carrier comprising a dispersing continuous aqueous phase and adispersed discontinuous oily phase) and which thus contain, in variousconcentrations, one or more conventional lipophilic and/or hydrophilicorganic screening agents including an aromatic function. These arecapable of selectively absorbing harmful UV radiation, such screeningagents (and their amounts) being selected as a function of the desiredsun protection factor SPF (the sun protection factor being expressedmathematically by the ratio of the irradiation time required to attainthe erythema-forming threshold with the UV screening agent to the timerequired to attain the erythema-forming threshold in the absence of UWscreening agent).

Other than their screening power, these compounds exhibiting anti-UVactivity must also have good cosmetic properties in compositionscomprised thereof, good solubility in the usual solvents, and inparticular fatty substances such as oils and greases, as well as goodresistance to water and to perspiration (remanence).

Among all of the aromatic compounds which are suited for this purpose,particularly well suited are the silicon-containing benzalmalonatecompounds described in EP-A-358,584 and in EP-A-392,882, both assignedto the assignee hereof. Admittedly, these compounds have goodliposolubility. However, they also comprise very long silicone chainsand, taking account of their bulk, their synthesis, as well as theirformulation into cosmetic compositions, is not without difficulty.Lastly, their cosmetic properties are not always satisfactory.

SUMMARY OF THE INVENTION

A major object of the present invention is the provision of novelcinnamamide, benzalmalonamide and benzalmalonate compounds bearingshort-chain silicone substituents on the aromatic moieties thereof,these novel compounds having, besides very good solubility in fattymaterials, improved cosmetic properties, and which otherwise avoid thosedisadvantages and drawbacks to date characterizing the state of thisart.

Even more specifically, it has now been found that by grafting at leastone cinnamamide, benzalmalonamide or benzalmalonate group onto ashort-chain silicone molecule, in particular onto a linear siliconechain comprising not more than six Si atoms, novel compounds areobtained which obviate the drawbacks of the screening agents of theprior art, these novel compounds having, other than veryhigh-performance screening properties, very good solubility in the usualorganic solvents and in particular fatty substances such as oils, aswell as excellent cosmetic properties, which render them particularlysuitable for use as sunscreens in, or for the formulation of, cosmeticcompositions suited for protecting the skin and/or the hair against thedeleterious effects of ultraviolet radiation. And, taking account oftheir relatively small size, these novel compounds are easier tosynthesize.

Thus, the present invention features novel compounds having one of theformulae (1) or (2) below: ##STR3## in which the radicals R, which maybe identical or different, are each a saturated or unsaturated, linearor branched C₁ -C₁₀ alkyl radical, a phenyl radical or a3,3,3-trifluoropropyl radical, at least 80% by number of the radicals Rbeing methyl radicals; the radicals B, which may be identical ordifferent, are each a radical R or a radical A; r is an integer rangingfrom 0 to 3, inclusive; s is 0 or 1 and if s is 0, at least one of thetwo radicals B is A; u is equal to 1 or 2; t is an integer ranging from0 to 5 inclusive; t+u is greater than or equal to 3; and A is a radicalof formula (3) below: ##STR4## wherein R₁ is a linear or branched C₁-C₁₀ alkoxy radical, a linear or branched C₁ -C₁₀ alkyl radical, alinear or branched C₂ -C₈ alkenyl radical or a radical --OSi(CH₃)₃, withthe proviso that two adjacent radicals R₁ may together form analkylidenedioxy radical in which the alkylidene radical has from 1 to 2carbon atoms, n is 0, 1 or 2, m is 0 or 1, Z is hydrogen or a radical--(C═O)YR₃, X and Y, which may be identical or different, are each anoxygen atom or a radical --NR₂ --, W is a saturated or unsaturated,linear or branched C₁ -C₆ alkanediyl radical, optionally substitutedwith a hydroxyl or saturated or unsaturated, linear or branched C₂ -C₈alkyl radical, R₂ is, independently, hydrogen or a C₁ -C₈ alkyl radical,R₃ is, independently, a linear or branched C₁ -C₁₂ alkyl radical, withthe proviso that R₂ and R₃, may together form a heterocycle, with theadded proviso that when Z═H, then X is the radical --NR₂ --.

DETAILED DESCRIPTION OF BEST MODE AND SPECIFIC/PREFERRED EMBODIMENTS OFTHE INVENTION

More particularly according to the present invention, by the term"heterocycle" is preferably intended a piperidino, morpholino,pyrrolidino or piperazino radical, optionally substituted in the4-position with a C₁ -C₆ alkyl radical.

The compounds of the invention differ from those of EP-A-392,882 in thatthe silicone chain(s) grafted onto the aromatic moieties of thecinnamamide, benzalmalonamide or benzalmalonate basic nuclei have notmore than six Si atoms when they are linear and not more than seven Siatoms when they are cyclic. Although, in this fashion, these compoundscomprise a short-chain silicone, they have excellent liposolubility andcan thus be used in large concentrations, which imparts to the finalcompositions very high protection factors. Moreover, they aredistributed uniformly in conventional cosmetic media containing at leastone fatty phase or a cosmetically acceptable organic solvent and canthus be topically applied to the hair or the skin to provide aneffective protective film. Furthermore, their cosmetic properties arevery good, i.e., in particular, these products are less sticky andprovide more softness than the screening silicones of the prior art.

In addition, the compounds of the invention have an excellent intrinsicscreening power with regard to UV-A and UV-B ultraviolet radiation.

These novel silicone-substituted cinnamamide, benzalmalonamide andbenzalmalonate compounds are thus useful sunscreens for human skin andhair. They are also useful photoprotective agents for plastics.

The cinnamamide, benzalmalonate or benzalmalonamide compounds of formula(1) or (2) advantageously have at least one of the followingcharacteristics:

R is methyl,

B is methyl,

r is 0 or 1,

s is 1,

t+u ranges from 3 to 5,

n is 0 or 1,

R₁ is methoxy,

R₃ is methyl or ethyl,

m is 1.

Preferably, the compounds according to the present invention arecompounds of formula (1) or (2) having all of the followingcharacteristics:

R is methyl,

B is methyl,

r=0,

s=1,

n=0,

m=1.

To prepare the compounds of formula (1) or (2), a synthesis can beemployed (route A) by carrying out a hydrosilylation reaction startingwith the corresponding siloxane derivative in which, for example, allthe radicals A are hydrogen atoms. This derivative is referred tohereinbelow as the SiH derivative.

The SiH groups can be present along the chain and/or at the ends of thechain. These SiH derivatives are compounds that are well known to thesilicone arts and are generally commercially available. They aredescribed, for example, in U.S. Pat. Nos. 3,220,972, 3,697,473 and4,340,709.

The SiH compounds corresponding to those of formulae (1) and (2) canthus be represented by formulae (4) and (5) below: ##STR5## in which R,r, s, t and u are as defined above in formulae (1) and (2); and theradicals B', which may be identical or different, are each a radical Ror a hydrogen atom.

A hydrosilylation reaction is carried out of this SiH derivative offormula (4) or (5) in the presence of a catalytically effective amountof a platinum catalyst, on an organic compound selected from among thoseof formula (6) below: ##STR6## in which R₁, R₃, X, Z, m and n are asdefined in formula (3) above and in which W' has the same definition asW in formula (3) above, but is terminated either with a double bond orwith a triple bond.

The hydrosilylation reaction is thus carried out according to one of thefollowing two reaction mechanisms: ##STR7##

The compounds of formula (6) are thus the following compounds:

(1) benzalmalonate compounds having the following formula: ##STR8## inwhich R₁, R₃, W', n and m are as defined in formula (6) above,

(2) benzalmalonamide compounds having the following formulae: ##STR9##in which R₁, R₂, R₃, n, m and W' are as defined in formula (6) above,

(3) cinnamamide compounds having the following formula: ##STR10## inwhich R₁, R₂, R₃, n, m and W' are as defined in formula (3) above.

Thus, benzalmalonate compounds which are particularly suitable for thepreparation of compounds according to the invention include diethyl4-methallyloxybenzylidenemalonate and diethyl4-allyloxybenzylidenemalonate, which are described in EP-392,882, anddiethyl 4-(2-propynyloxy)benzylidenemalonate described in WO-92/20690.

Another route (route B) for the synthesis of the compounds of formulae(1) and (2) entails, in a first step, hydrosilylating a benzaldehyde offormula (7) below: ##STR11## in which W', R₁, m and n are as defined informula (6) above, with a compound of formula (4) or (5) below:##STR12## in which R, r, s, t and u are as defined above in formulae (1)and (2), and the radicals B', which may be identical or different, areeach a radical R or a hydrogen atom, to prepare the correspondingsilicone benzaldehyde.

In a second step, an organic compound having formula (8) below:##STR13## in which Z, X and R₃ are as defined in formula (6) above, isreacted with this corresponding silicone benzaldehyde.

The compounds of formula (8) in the event that X═O are prepared byalkylation of the corresponding acid with an alkyl halide (Hal) in thepresence of a base, according to the following reaction scheme:

    ZCH.sub.2 COOH+Hal-R.sub.3 +NaOH→(8)+Hal-Na

The compounds of formula (7) in the event that X═NR₃ are prepared byreaction of the corresponding acid chloride with an amine according tothe following reaction scheme:

    ZCH.sub.2 COCl+H.sub.2 NR.sub.2 →(8)+HCl

The compounds of formula (7) in the event where m=1 are prepared byalkylation of the corresponding hydroxybenzaldehyde derivative with anunsaturated halide derivative.

The compounds of formula (7) in the event that m=0 are prepared byClaisen rearrangement of the above derivatives.

Thus, exemplary benzaldehydes which are particularly suitable for thepreparation of the compounds according to the invention include3-methallyloxybenzaldehyde and 4-methallyloxybenzaldehyde, which aredescribed in DE-2,108,932.

The present invention also features compositions comprising a compoundof formula (1) or (2) formulated into a suitable support or mediumtherefor. The support can be, for example, a plastic. It can also besuitable for topical application. In this instance, the compositionaccording to the invention is a cosmetic composition which comprises acosmetically acceptable vehicle, diluent or carrier.

Preferably, the compositions according to the invention are formulatedto protect sensitive material against ultraviolet radiation, inparticular solar radiation, comprising an effective amount of at leastone compound of formulae (1) or (2). In a preferred embodiment of theinvention, such compositions are for the photoprotection of the skinand/or the hair.

The compounds of formula (1) or (2) are generally formulated into thecompositions of the invention in proportions of from 0.1% to 20% byweight, preferably from 0.5% to 10% by weight, relative to the totalweight of the composition.

The compositions according to the invention can, of course, contain oneor more complementary hydrophilic or lipophilic sunscreens that areactive in the UV-A and/or UV-B range (absorbers), other than the subjectcompounds. These complementary screening agents are advantageouslyselected, in particular, from among the cinnamic derivatives, salicylicderivatives, camphor derivatives, triazine derivatives, benzophenonederivatives, dibenzoylmethane derivatives, β,β-diphenylacrylatederivatives, p-aminobenzoic acid derivatives, and the screening polymersand screening silicones described in WO-93/04665. Other examples oforganic screening agents are provided in EP-A-0,487,404.

The compositions according to the invention may also contain agents forthe artificial tanning and/or browning of the skin (self-tanning agents)such as, for example, dihydroxyacetone (DHA).

The compositions according to the invention may also contain pigments ornanopigments (average size of the primary particles: generally rangingfrom 5 nm to 100 nm, preferably from 10 nm to 50 nm) of coated oruncoated metal oxides, for example nanopigments of titanium dioxide(amorphous or crystallized in rutile and/or anatase form), of ironoxide, of zinc oxide, of zirconium oxide or of cerium oxide, which areall UV-photoprotective agents that are per se well known to this art.Standard coating agents therefor, include, moreover, alumina and/oraluminum stearate. Such coated or uncoated metal oxide nanopigments aredescribed, in particular, in EP-A-0,518,772 and EP-A-0,518,773.

The subject photoprotective compositions may also comprise typicaladditives and adjuvants in the cosmetics field, such as fattysubstances, organic solvents, silicones, thickeners, softeners,complementary sunscreens, anti-foaming agents, moisturizers, fragrances,preservatives, surfactants, fillers, sequestering agents, anionic,cationic, nonionic or amphoteric polymers, or mixtures thereof,propellants, basifying or acidifying agents, dyes, colorants, pigmentsor nanopigments, in particular those intended to ensure a complementaryphotoprotective effect by physically blocking ultraviolet radiation, orany other ingredient usually used in cosmetics, in particular for theformulation of sunscreen compositions.

Among the organic solvents, exemplary are the lower alcohols and polyolssuch as ethanol, isopropanol, propylene glycol, glycerol and sorbitol.

Exemplary fatty substances include an oil or a wax or mixtures thereof,fatty acids, fatty acid esters, fatty alcohols, petroleum jelly,paraffin, lanolin, hydrogenated lanolin or acetylated lanolin. The oilscan be selected from among animal, plant, mineral or synthetic oils, andin particular hydrogenated palm oil, hydrogenated castor oil, liquidpetroleum jelly, liquid paraffin, purcellin oil, volatile ornon-volatile silicone oils, and isoparaffins.

Naturally, one skilled in this art will take care to select the optionalcomplementary compound(s) indicated above and/or the amounts thereofsuch that the advantageous properties intrinsically associated with thecompounds of this invention are not, or are not substantially, adverselyaffected by the addition(s) envisaged.

The cosmetic compositions of the invention are well suited forprotecting the human epidermis or the hair against the damaging effectsof ultraviolet rays, whether as a sunscreen composition or as a makeupproduct.

The subject compositions are advantageously formulated as lotions,thickened lotions, gels, creams, milks, powders or as solid sticks andcan, optionally, be packaged as an aerosol and be in the form of a foamor a spray.

When the cosmetic compositions according to the invention are moreparticularly intended for protecting the human epidermis against UVirradiation or as sunscreen compositions, they can be formulated assuspensions or dispersions in solvents or fatty substances, or asemulsions (in particular of O/W or W/O type, but preferably O/W type)such as a cream or a milk, a vesicle dispersion, or as ointments, gels,solid sticks or aerosol foams. The emulsions can also contain anionic,nonionic, cationic or amphoteric surfactants.

When the cosmetic compositions according to the invention are used toprotect the hair, they may be in the form of a shampoo, a lotion, a gelor a rinse-out composition to be applied before or after shampooing,before or after dyeing or bleaching, before, during or afterpermanent-waving or straightening of the hair, a styling or treatinglotion or gel, a blow-drying or hair-setting lotion or gel, a hairlacquer or a composition for permanent-waving, straightening, dyeing orbleaching the hair.

When the cosmetic compositions according to the invention are formulatedas makeup products for the eyelashes, the eyebrows, the skin or thehair, such as skin treatment creams, foundations, lipsticks, eyeshadows,blushers, eyeliners, mascara or coloring gels, same may be in anhydrousor aqueous, solid or pasty form, for example oil-in-water orwater-in-oil emulsions, suspensions or, alternatively, gels.

This invention also features the subject compounds formulated intocompositions well suited for photoprotecting sensitive material againstultraviolet radiation, in particular solar radiation.

This invention also features formulating a compound of formulae (1) or(2) into medicinal products for combatting the harmful effects of UVradiation.

The present invention also features use of a compound of formula (1) or(2) as an agent for screening out UV radiation, in particular forcontrolling the color of the skin.

Lastly, the present invention also features a non-therapeutic processfor protecting the skin and/or the hair against the deleterious effectsas ultraviolet radiation, in particular solar radiation, comprisingapplying to the skin or the hair an effective sunscreen amount of thecosmetic composition defined above, or of a compound of formula (1) or(2).

Too, this invention features a non-therapeutic process for controllingthe variation in skin color due to UV radiation, which includes applyingto the skin an effective amount of the cosmetic composition definedabove, or of a compound of formula (1) or (2).

In order to further illustrate the present invention and the advantagesthereof, the following specific examples are given, it being understoodthat same are intended only as illustrative and in nowise limitative.

EXAMPLE 1 Preparation of diethyl4-[2-methyl-3-[1,3,3,3-tetra-methyl-1-[(trimethylsilyl)oxy]disiloxanyl]propyloxy]-benzylidenemalonateaccording to route A ##STR14##

To a solution of diethyl 4-methallyloxy-benzylidenemalonate (15.9 g,0.05 mol) and catalyst (complex containing 3-3.5 wt % of Pt incyclovinyl-methylsiloxane, marketed by Huls under the trademark PetrarchPC085 : 100 μl) in 30 ml of dry toluene heated to 70° C., were addeddropwise over 30 minutes 12.23 g (0.055 mol) of heptamethyltrisiloxane.The mixture was maintaied at this temperature for 6 hours. The reactionmixture was concentrated and, after chromatography on silica (eluent:95/5 heptane/ethyl acetate), 14.8 g (yield: 55%) of a colorless oil wereobtained, having the following characteristics:

(i) UV (ethanol) λ_(max) =314 nm, ε_(max) =25,000

(ii) Elemental analysis for C₂₅ H₄₄ O₇ Si₃

    ______________________________________                                        theory:     C: 55.52   H: 8.20   Si: 15.58                                      found: C: 55.31 H: 8.16 Si: 15.29                                           ______________________________________                                    

EXAMPLE 2 Preparation of diethyl3-[2-methyl-3-[1,3,3,3-tetra-methyl-1-[(trimethylsilyl)oxy]disiloxanyl]propyloxy]-benzylidenemalonateaccording to route B ##STR15##

(a) First step: Preparation of3-[2-methyl-3-[1,3,3,3-tetramethyl-1-[(trimethylsilyl)oxy]disiloxanyl]-propyloxy]benzaldehyde:

To a solution of 3-methallyloxybenzaldehyde (20 g, 0.113 mol) andcatalyst (complex containing 3-3.5 wt % of Pt incyclovinylmethylsiloxane, marketed by Huls under the trademark PetrarchPC085 : 200 μl) in 40 ml of dry toluene heated to 80° C., were addeddropwise over 30 minutes 12.23 g (0.055 mol) of heptamethyltrisiloxane.The mixture was maintained at this temperature for 16 hours. Thereaction mixture was concentrated and, after chromatography on silica(eluent: 90/10 heptane/ethyl acetate), 26.4 g (yield: 59%) of acolorless oil of3-[2-methyl-3-[1,3,3,3-tetramethyl-1-[(trimethylsilyl)-oxy]disiloxanyl]propyloxy]benzaldehydewere obtained.

(b) Second step: Preparation of diethyl3-[2-methyl-3-[1,3,3,3-tetramethyl-1-[(trimethylsilyl)oxy]-disiloxanyl]propyloxy]benzylidenemalonate:

A mixture of the above compound (a) (4 g, 0.0085 mol) and diethylmalonate (1.6 g, 0.01 mol) in 15 ml of toluene was refluxed for 3 hoursin the presence of 0.1 ml of piperidine and 0.06 ml of acetic acid. Thereaction mixture was concentrated and, after chromatography on silica(eluent: 50/50 heptane/dichloromethane), 3.5 g (yield: 76%) of acolorless oil were obtained, having the following characteristics:

(i) UV (ethanol) λ_(max) =280 nm, ε_(max) =16,700

λ_(max) =320 nm, ε_(max) =3,400

(ii) Elemental analysis for C₂₅ H₄₄ O₇ Si₃

    ______________________________________                                        theory:        C: 55.52     H: 8.20                                             found: C: 55.77 H: 8.01                                                     ______________________________________                                    

EXAMPLE 3 Preparation of ethyl3-[4-[2-methyl-3-[1,3,3,3-tetra-methyl-1-[(trimethylsilyl)oxy]disiloxanyl]propyloxy]-phenyl]-2-(piperidine-1-carbonyl)acrylateaccording to route B ##STR16##

(a) First step: Preparation of4-[2-methyl-3-[1,3,3,3-tetramethyl-1-[(trimethylsilyl)-oxy]disiloxanyl]propyloxy]benzaldehyde

To a solution of 4-methallyloxybenzaldehyde (17.62 g, 0.1 mol) andcatalyst (complex containing 3-3.5 wt % of Pt incyclovinylmethylsiloxane, marketed by Huls under the trademark PetrarchPCO85 : 300 μl) in 50 ml of dry toluene heated to 80° C., were addeddropwise over 30 minutes 24.47 g (0.11 mol) of heptamethyltrisiloxane.The mixture was maintained at this temperature for 26 hours. Thereaction mixture was maintained concentrated and, after distillation ata pressure of 0.1 mmHg (fractions distilling at 135-141° C.), 34.1 g of4-[2-methyl-3-[1,3,3,3-tetramethyl-1-[(trimethylsilyl)oxy]disiloxanyl]-propyloxy]benzaldehyde(yield: 85%) were obtained in the form of a colorless oil.

(b) Second step: Preparation of ethyl3-[4-[2-methyl-3-[1,3,3,3-tetramethyl-1-[(trimethylsilyl)oxy]disiloxany]propyloxy]phenyl]-2-(piperidine-1-carbonyl)acrylate:

A mixture of the above compound (a) (18.18 g, 0.046 mol) and diethylmalonate (9.61 g, 0.06 mol) in 20 ml of toluene was refluxed for 7 hoursin the presence of 4.5 ml of piperidine and 1.5 ml of acetic acid. Thereaction mixture was concentrated and, after chromatography on silica(eluent: 95/5 heptane/dichloromethane) of the final fractions, 8 g(yield: 30%) of a viscous colorless oil were obtained, having thefollowing characteristics:

UV (ethanol) λ_(max) =315 nm, ε_(max) =19, 860

EXAMPLE 4 Preparation of diethyl4-[3-[1,3,3,3-tetramethyl-1-[(trimethylsilyl)oxy]disiloxanyl]propyloxy]-benzylidenemalonateaccording to route A: ##STR17##

To a mixture of diethyl 4-allyloxy-benzylidenemalonate (17.7 g, 0.058mol) and catalyst (complex containing 3-3.5 wt % of Pt incyclovinylmethylsiloxane, marketed by Huls under the trademark PetrarchPC085 : 400 μl) heated to 60° C., were added dropwise over 30 minutes14.23 g (0.064 mol) of heptamethyltrisiloxane. The mixture wasmaintained left at this temperature for 1 hour. The excessheptamethyltrisiloxane was removed under vacuum. The residue waspurified by chromatography on silica (eluent: 96/4 heptane/ethylacetate) in order to obtain 11.4 g (yield: 37%) of clean fractions of acolorless oil having the following characteristics:

(i) UV (ethanol) λ_(max) =314 nm, ε_(max) =25,420

(ii) Elemental analysis for C₂₄ H₄₂ O₇ Si₃

    ______________________________________                                        theory:        C: 54.71     H: 8.04                                             found: C: 54.84 H: 8.11                                                     ______________________________________                                    

EXAMPLE 5 Preparation of dimethyl4-[3-[1,3,3,3-tetramethyl-1-[(trimethylsilyl)oxy]disiloxanyl]propyloxy]-benzylidenemalonateaccording to route A: ##STR18##

To a mixture of dimethyl 4-allyloxybenzylidenemalonate (8.55 g, 0.031mol) and catalyst (complex containing 3-3.5 wt % of Pt incyclovinyl-methylsiloxane, marketed by Huls under the trademark PetrarchPCO85 : 100 μl) in 10 ml of toluene heated to 60° C., were addeddropwise over 30 minutes 7.97 g (0.034 mol) of heptamethyltrisiloxane.The mixture was maintained at this temperature for 6 hours. The excessheptamethyltrisiloxane was removed under vacuum. The residue waspurified by chromatography on silica (eluent: 96/4 heptane/ethylacetate) in order to obtain 1.5 g (yield: 11%) of clean fractions of acolorless oil having the following characteristics:

(i) UV (ethanol) λ_(max) =315 nm, ε_(max) =25,640

(ii) Elemental analysis for C₂₂ H₃₈ O₇ Si₃

    ______________________________________                                        theory:        C: 52.98     H: 7.68                                             found: C: 52.64 H: 7.59                                                     ______________________________________                                    

EXAMPLE 6 Preparation of diethyl4-[3-[1,3,3,3-tetramethyl-1-[(trimethylsilyl)oxy]disiloxanyl]-2-propenyloxy]-benzylidenemalonateand diethyl4-[3-[1,3,3,3-tetra-methyl-1-[(trimethylsilyl)oxy]disiloxanyl]-2-vinylidene-ethanoxy]benzylidenemalonate##STR19##

To a mixture of diethyl 4-(2-propynyloxy)-benzylidenemalonate (15.1 g,0.05 mol) and catalyst (complex containing 3-3.5 wt % of Pt incyclovinylmethylsiloxane, marketed by Huls under the trademark PetrarchPC085 : 100 μl) in 30 ml of toluene heated to 90° C., were addeddropwise over 30 minutes 12.2 g (0.055 mol) of heptamethyltrisiloxane.The mixture was maintained at this temperature for 1 hour 30 minutes.The excess heptamethyltrisiloxane was removed under vacuum. The residuewas purified by chromatography on silica (eluent: CH₂ Cl₂) in order toobtain 12.1 g (yield: 46%) of clean fractions of a colorless oil. ProtonNMR shows that a mixture of two compounds was obtained in a 9/1 ratio.

(i) UV (ethanol) λ_(max) =313 nm, ε_(max) =26,530

(ii) Elemental analysis for C₂₂ H₃ 80₇ Si₃

    ______________________________________                                        theory:     C: 52.98   H: 7.68   Si: 16.89                                      found: C: 52.62 H: 7.72 Si: 16.80                                           ______________________________________                                    

EXAMPLE 7

One specific example of a sunscreen emulsion having the followingcomposition is given below (the amounts are expressed in % by weightrelative to the total weight of the composition):

    ______________________________________                                        (a) 80/20 mixture of cetylstearyl alcohol                                                                 7%                                                  and oxyethylenated cetylstearyl alcohol (33 EO)                               marketed under the trademark "Dehsconet 390" by                               Tensia,                                                                       (b) mixture of glyceryl mono- and 2%                                          distearate marketed under the trademark                                       "Cerasynth SD" by ISP,                                                        (c) cetyl alcohol, 1.5%                                                       (d) polydimethylsiloxane marketed 1.5%                                        under the trademark "DC200 Fluid" by Dow Corning,                             (e) C.sub.12 --C.sub.15  alkyl benzoate marketed 15%                          under the trademark "Finsolv TN" by Finetex,                                  (f) compound of Example 2, 5%                                                 (g) glycerol, 20%                                                             (h) preservatives qs                                                          (i) demineralized water qs 100%                                             ______________________________________                                    

This O/W sunscreen emulsion was formulated according to standardtechniques for the preparation of emulsions, by dissolving the screeningagent in the fatty phase containing the emulsifiers, heating this fattyphase to about 70-80° C. and adding, with vigorous stirring, the waterheated to the same temperature. Stirring was continued for 10 to 15minutes, the mixture was then permitted to cool with moderate stirringand lastly, at about 40° C., the preservatives were added.

A sunscreen cream particularly effective against UV radiation was thusobtained.

While the invention has been described in terms of various preferredembodiments, the skilled artisan will appreciate that variousmodifications, substitutions, omissions, and changes may be made withoutdeparting from the spirit thereof. Accordingly, it is intended that thescope of the present invention be limited solely by the scope of thefollowing claims, including equivalents thereof.

What is claimed is:
 1. A silicone-substituted cinnamamide,benzalmalonamide or benzalmalonate compound having one of the followingstructural formulae (1) or (2): ##STR20## in which the radicals R, whichmay be identical or different, are each a saturated or unsaturated,linear or branched C₁ -C₁₀, alkyl radical, a phenyl radical or a3,3,3-trifluoropropyl radical, at least 80% by number of the radicals Rbeing methyl radicals; the radicals B, which may be identical ordifferent, are each a radical R or a radical A; r is an integer rangingfrom 0 to 3, inclusive; s is 0 or 1 and, if s is 0, at least one of thetwo radicals B is A; u is equal to 1 or 2; t is an integer ranging from0 to 5, inclusive; t+u is greater than or equal to 3; and A is a radicalof formula (3) below: ##STR21## wherein R₁ is a linear or branched C₁-C₂₀ alkoxy radical, a linear or branched C₁ -C₁₀ alkyl radical, alinear or branched C₂ -C₈ alkenyl radical or a radical --OSi(CH₃)₃, withthe proviso that two adjacent radicals R₁ may together form analkylidenedioxy radical in which the alkylidene radical has from 1 to 2carbon atoms, n is 0, 1 or 2, m is 0 or 1, Z is hydrogen or a radical--(C═O)YR₃, X and Y, which may be identical or different, are each anoxygen atom or a radical --NR₂ --, W is a saturated or unsaturated,linear or branched C₁ -C₆ alkanediyl radical, optionally substitutedwith a hydroxyl or saturated or unsaturated, linear or branched C₂ -C₈alkyl radical, R₂ is, independently, hydrogen or a C₁ -C₈ alkyl radical,and R₃ is, independently, a linear or branched C₁ -C₁₂ alkyl radical,with the proviso that R₂ and R₃ may together form a heterocycle, andwith the added proviso that when Z═H, then X is the radical --NR₂ --. 2.A silicone-substituted compound as defined by claim 1, wherein formulae(1) or (2), at least one of the following definitions exists:R ismethyl, B is methyl, r is 0 or 1, s is 1, t+u ranges from 3 to 5, n is 0or 1, R₁ is methoxy, R₃ is methyl or ethyl, and/or m is
 1. 3. Asilicone-substituted compound as defined by claim 1, wherein formulae(1) or (2), each of the following definitions exists:R is methyl, B ismethyl, r=0, s=1, n=0, and m=1.
 4. A silicone-substituted compound asdefined by claim 1, selected from among diethyl4-[2-methyl-3-[1,3,3,3-tetramethyl-1-[(trimethylsilyl)oxy]-disiloxanyl]propyloxy]-benzylidenemalonate;diethyl3-[2-methyl-3-[1,3,3,3-tetramethyl-1-[(trimethylsilyl)-oxy]disiloxanyl]propyloxy]-benzylidenemalonate;ethyl3-[4-[2-methyl-3-[1,3,3,3-tetramethyl-1-[(trimethylsilyl)oxy]disiloxanyl]propyloxy]phenyl]-2-(piperidine-1-carbonyl)acrylate; diethyl4-[3-[1,3,3,3-tetramethyl-1-[(trimethylsilyl)oxy]disiloxanyl]propyloxy]-benzylidenemalonate;dimethyl4-[3-[1,3,3,3-tetramethyl-1-[(trimethylsilyl)oxy]disiloxanyl]propyloxy]-benzylidenemalonate;diethyl4-[3-[1,3,3,3-tetramethyl-1-[(trimethylsilyl)oxy]disiloxanyl]-2-propenyloxy]-benzylidenemalonate;and diethyl4-[3-[1,3,3,3-tetramethyl-1-[(trimethylsilyl)oxy]disiloxanyl]-2-vinylidene-ethanoxy]benzylidenemalonate.5. A process for the preparation of a silicone-substituted compound asdefined by claim 1, comprising hydrosilylating a compound of thefollowing formula (6): ##STR22## in which R₁, R₃, X, Z and n are asdefined as in formula (3) and in which W' is W, except having a double-or triple-bond endgroup, in the presence of a catalytically effectiveamount of a platinum catalyst, with an SiH compound having one of thefollowing structural formulae (4) or (5): ##STR23## in which R, r, s, tand u are defined as in formulae (1) and (2); and the radicals B', whichmay be identical or different, are each a radical R or a hydrogen atom.6. A process for the preparation of a silicone-substituted compound asdefined by claim 1, comprising first reacting a benzaldehyde having thestructural formula (7): ##STR24## wherein R₁ is a linear or branched C₁-C₁₀ alkoxy radical, a linear or branched C₁ -C₁₀ alkyl radical, alinear or branched C₂ -C₈ alkenyl radical or a radical --OSi(CH₃)₃, withthe proviso that two adjacent radicals R₁ may together form analkylidenedioxy radical in which the alkylidene radical has from 1 to 2carbon atoms, n is 0, 1 or 2, m is 0 or 1, and W' is a saturated orunsaturated, linear or branched C₁ -C₆ alkanediyl radical, optionallysubstituted with a hydroxyl or saturated or unsaturated, linear orbranched C₂ -C₈ alkyl radical, with the proviso that W' has a double- ortriple-bond endgroup, with an SiH compound having one of the followingstructural formulae (4) or (5): ##STR25## in which R, r, s, t and u aredefined as in formulae (1) and (2); and the radicals B', which may beidentical or different, are each a radical R or a hydrogen atom, andnext reacting the silicone benzaldehyde thus formed with an organiccompound having the structural formula (8): ##STR26## in which Z, X andR₃ are defined as in formula (3).
 7. A photoprotective cosmeticcomposition suited for photoprotecting the skin and/or hair against thedeleterious effects of UV radiation, comprising an effectiveUV-screening amount of at least one silicone-substituted compound asdefined by claim 1, formulated into a topically applicable cosmeticallyacceptable vehicle, diluent or carrier therefor.
 8. The photoprotectivecosmetic composition as defined by claim 7, comprising from 0.1% to 20%by weight of said at least one silicone-substituted compound.
 9. Thephotoprotective composition as defined by claim 8, comprising from 0.5%to 10% by weight of said at least one silicone-substituted compound. 10.The photoprotective composition as defined by claim 7, formulated as alotion, gel, cream, milk, emulsion, powder, solid stick, foam, spray, orointment.
 11. The photoprotective composition as defined by claim 7,formulated as a shampoo, hair dye, hair bleach, hair wave, hair lacquer,or hair straightener.
 12. The photoprotective composition as defined byclaim 7, further comprising at least one additional UV-A and/or UV-Bsunscreen.
 13. The photoprotective composition as defined by claim 7,further comprising at least one active agent for the artificial tanningand/or browning of human skin.
 14. The photoprotective composition asdefined by claim 7, further comprising a photoprotecting effectiveamount of at least one inorganic pigment or nanopigment.
 15. Thephotoprotective composition as defined by claim 7, further comprising atleast one fatty substance, solvent, silicone, thickener, softener,anti-foaming agent, moisturizer, fragrance, preservative, surfactant,filler, sequestering agent, polymer, basifying or acidifying agent, orcolorant.
 16. A UV-sensitive shaped article, containing an effectiveUV-photoprotecting amount of at least one silicone substituted compoundas defined by claim
 1. 17. The shaped article as defined by claim 16,comprising a plastic.
 18. A method for photoprotecting human skin and/orhair against the deleterious effects of UV irradiation, comprisingtopically applying thereto an effective UV-screening amount of thephotoprotective composition as defined by claim
 7. 19. A method forcontrolling variation in skin color promoted by UV irradiation,comprising topically applying thereto an effective UV-screening amountof the photoprotective composition as defined by claim 7.